I’ve read ever since middle school about how the Romans, Greeks, Egyptians, etc. all used salt as a form of currency. Its ability to stave off rotting of meat was extremely valuable for long trips on the ocean and across land. Gotcha. My question is: isn’t salt really easy to obtain? Just put a pot of salt water over a fire, go hunt and gather for a while, and then come back a few hours later and voila! Salt! Did they not figure this out, or what?
You have to feed the fire, and that takes enough wood so that rather than going off to hunt and gather for a while, you’ll spend all your time gathering.
1.) It’s a lot of work if you want a lot of salt. Easier to find a deposit and breakm off what you need.
2.) Salt made that way isn’t pure sodium chloride – it contains a fair amount of Magnesium sulfate and other “salts” that (I’m told) affect the flavor.
Richard Burton, in one of his books, gave a “recipe” for preparing NaCl-enriched sea salt. It involved “filtering” water through the dried mixture.
3.) Sea Salt made that way certainly would work in the absence of other salt – read Hemingway’s “The Old Man and the Sea”, where the hero talks of splashing sea water into the boat seat so it’ll dry and leave salt. Or watch “Gandhi” and pay attention to the scenes where they talk about going to the sea to “make salt”.
It is easy to get in the correct regions. Being a necessity many rulers limited it’s accessibility and heavily taxed it. You could just go down to the ocean and evaporate water to get it. The processing by most persons was illegal.
That’s what made me start to think about this. If he and his followers were able to produce a significant amount of salt from sea water, what would stop others from doing the same? That said, I admit that I overlooked some of the practicality of it (which you guys pointed out). It just seems kind of silly to me to have a currency made out of stuff that the average joe could make if he so chooses.
The Book of Salt, by Monique Truong (http://www.houghtonmifflinbooks.com/readers_guides/truong_salt.shtml) goes into this in some detail.
But basically Squink and HarmDiscord are both right: it is easy in theory, but takes a fair amount of work to produce in bulk amounts, and rulers tried to take control over it.
Salt by Mark Kurlansky goes into more detail than you can imagine about this. A fascinating read.
Whoops – wrong book.
Salt: A World History by Mark Kurlansky (http://www.amazon.com/gp/product/0142001619/002-6214894-4542429?v=glance&n=283155) is the book I meant. It talks all about salt and its production.
The book by Monique Truong is a novel about Gertrude Stein, a Vietnamese cook, and the use of salt. Interesting, but nothing much about the history of salt.
That date may be off though:
Where exactly do you get salt water from, if you aren’t right on the coast?
Even if you are on the coast, as Squink mentions boiling the salt water takes fuel. If you try to manufacture a lot of salt that way (enough to spare to ship elsewhere) it will take you a lot of effort to get enough wood, especially since you will probably soon cut down the closest forests.
If you are in a sunny dry area near the coast you can make salt with much less effort by making evaporation ponds and letting the sunlight do the work for you. But in much of western Europe the climate is too rainy to make that practical for much of the year. If it rains on your evaporation pond, it will undo all the work the sun did previously.
Salt was in limited supply because it either had to be mined, or was only easily made in limited coastal areas. Most places had to obtain it by trading.
Salt can be collected by letting the salt water evaporate in shallow manmade pools. Some places have salt springs also, and some dry salt can be gathered near the water line. In land bodies of water like the Great Salt Lake and the Dead Sea will provide salt at the water line.
James Michener wrote in his book “Centennial” about the shortages of salt and methods of obtaining it the early days of the settling of America. Salt is one of those things that we take for granted as an abundant commodity that used to be in short supply in many areas.
Sorry, I left that bit out of the OP - I was thinking that since (most) early civilizations were near or had access to the ocean that salt water would be relatively easy to attain. What about a blacksmith or something of that sort - which would have a heat source going pretty often anyway - couldn’t (s)he make a little extra income from boiling some salt water?
You need a ton of energy to get salt. Water has a specific heat of 4 J/K/gm and a latent heat of 2200 J/g so 1kg of water at 25C would take 2.5MJ to boil off. Wood has an energy density or 13.8MJ per Kg and salt water is roughly 3.5% salt so under ideal conditions, to get 1kg of salt would require 70MJ or 5 Kg of wood. Throw in a fudge factor of 3 or so and you would need about 15Kg of wood for every Kg of salt.
I’m not doubting your math, but that makes obtaining salt seem pretty easy. A kilogram of salt goes a pretty long way, and 15kg of wood is only an armful or so of wood.
And how much salt do you need to make bacon? Or pickles?
If you’re talking about salt as a mere condiment, we don’t use much — but our bacon and ham and Chinese food comes with all the salt we need, straight from the store.
I’m not competent to comment on the theoretical side, but here’s an account of the practical process of extracting salt from sea water on the North East coast of England in the early eighteenth century:
(From A Portrait of Achievement by D. H. Williams. Reproduced by kind permission of the author.)
1 Tun = 252 imperial gallons = 954 litres
1 Chaldron = 256 gallons = 1,163.8 litres
So in a week, they consumed 16,293.2 litres of coal to produce 2,385 litres of salt, or about 6.8 litres of coal per litre of salt.
It seems it was also necessary to clarify the brine with the whites of eggs or the blood of sheep and black cattle, prior to boiling.
Our Inorganic Chem teacher in college told us that one reason for the historical importance of the Spanish salt industry in industrial times was that in northern countries you can’t just use the Spanish method of creating saltwater pools and letting them dry up: they’d boil water in copper cauldrons.
The salt obtained that way had a high copper content (chloride is quite good at eating up metals), so when used on fish the fish ended up going green, which in turn made housewives go YUCK. Sun-dried salt didn’t have the copper, so the fishing industry started importing it.
While I don’t have an actual web-based quote, I have seen the saltwater pools. I used to work for the company that currently owns Morton Salt and was quite shocked to find out that they didn’t sun-dry salt but much of it is mined. Mined? Gosh…
Have any cite for this? I would think that most early civilizations were near or had access to FRESH water - lakes, rivers, or streams. Not so sure about ocean waters.
To the OP: I second the recommendation for this book. Reading it, you will be surprised at just how difficult it was to make salt, how instrumental salt was to society and trade, and how many interesting innovations came about because of the search for salt.